Is Find Largest Value in Each Tree Row easy or hard?

The problem is rated Medium because it requires understanding tree traversal patterns and managing level-based computations. Developers familiar with BFS level-order traversal usually solve it quickly once they recognize that each tree row corresponds to a BFS level.

Find Largest Value in Each Tree Row Python/Java solution

Python and Java solutions typically implement BFS using a queue or DFS with recursion. Both versions maintain a list that stores the maximum value per level while traversing the tree. Each solution runs in O(n) time and requires O(w) or O(h) space depending on the traversal strategy.

How to solve Find Largest Value in Each Tree Row in O(n)?

Traverse the tree once while maintaining the maximum value for each level. With BFS, process nodes level by level using a queue and track the largest value in each iteration. With DFS, pass the current depth during recursion and update the maximum value stored for that level. Both approaches ensure each node is processed only once.

What is the best approach for Find Largest Value in Each Tree Row?

Breadth-First Search (BFS) using level-order traversal is the most straightforward approach. It processes the tree one level at a time using a queue and computes the maximum value for each row during the traversal. The algorithm runs in O(n) time and uses O(w) space where w is the maximum width of the tree.

Is Find Largest Value in Each Tree Row asked at Google/Amazon/Meta?

Variants of this problem appear in interviews at large tech companies because it tests tree traversal fundamentals. Companies like Amazon, Google, and Meta frequently ask binary tree problems that require BFS level traversal or DFS with depth tracking.

What data structure is used in Find Largest Value in Each Tree Row?

The BFS approach uses a queue to process nodes level by level. The DFS approach relies on recursion (or an explicit stack) along with an array or list that stores the maximum value found for each depth level.

What is the time complexity of Find Largest Value in Each Tree Row?

The optimal time complexity is O(n) because every node in the binary tree is visited exactly once. Both BFS level-order traversal and DFS with depth tracking achieve this complexity while computing the maximum value for each level.

Description Solution Video 6:09

515. Find Largest Value in Each Tree Row

Medium66.3% acceptance8 companies

Given the root of a binary tree, return an array of the largest value in each row of the tree (0-indexed).

Example 1:

Input: root = [1,3,2,5,3,null,9]
Output: [1,3,9]

Example 2:

Input: root = [1,2,3]
Output: [1,3]

Constraints:

The number of nodes in the tree will be in the range [0, 10⁴].
-2³¹ <= Node.val <= 2³¹ - 1

Asked at 8 companies

Josh Technology LinkedIn Bloomberg Apple

Google Amazon Microsoft Meta

Topics

6:09

Still stuck?Read 4 approaches, or watch a walkthrough.

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LanguageLoading editor…

1# Definition for a binary tree node.
2# class TreeNode:
3#     def __init__(self, val=0, left=None, right=None):
4#         self.val = val
5#         self.left = left
6#         self.right = right
7class Solution:
8    def largestValues(self, root: Optional[TreeNode]) -> List[int]:
9        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

[1,3,2,5,3,null,9]

Input

[1,2,3]

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